<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
	<head>
		<title>How To Include This Module</title>
<link href="../docs-assets/Breadcrumbs.css" rel="stylesheet" rev="stylesheet" type="text/css">
		<meta name="viewport" content="width=device-width initial-scale=1">
		<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
		<meta http-equiv="Content-Language" content="en-gb">

<link href="../docs-assets/Contents.css" rel="stylesheet" rev="stylesheet" type="text/css">
<link href="../docs-assets/Progress.css" rel="stylesheet" rev="stylesheet" type="text/css">
<link href="../docs-assets/Navigation.css" rel="stylesheet" rev="stylesheet" type="text/css">
<link href="../docs-assets/Fonts.css" rel="stylesheet" rev="stylesheet" type="text/css">
<link href="../docs-assets/Base.css" rel="stylesheet" rev="stylesheet" type="text/css">
<link href="../docs-assets/Colours.css" rel="stylesheet" rev="stylesheet" type="text/css">
		
	</head>
	<body class="commentary-font">
		<nav role="navigation">
		<h1><a href="../index.html"><img src="../docs-assets/Inform.png" height=72> </a></h1>
<ul><li><a href="../index.html">home</a></li>
</ul><h2>Compiler</h2><ul>
<li><a href="../structure.html">structure</a></li>
<li><a href="../inbuildn.html">inbuild</a></li>
<li><a href="../inform7n.html">inform7</a></li>
<li><a href="../intern.html">inter</a></li>
<li><a href="../services.html">services</a></li>
<li><a href="../secrets.html">secrets</a></li>
</ul><h2>Other Tools</h2><ul>
<li><a href="../inblorbn.html">inblorb</a></li>
<li><a href="../inform6.html">inform6</a></li>
<li><a href="../inpolicyn.html">inpolicy</a></li>
</ul><h2>Resources</h2><ul>
<li><a href="../extensions.html">extensions</a></li>
<li><a href="../kits.html">kits</a></li>
</ul><h2>Repository</h2><ul>
<li><a href="https://github.com/ganelson/inform"><img src="../docs-assets/github.png" height=0> github</a></li>
</ul><h2>Related Projects</h2><ul>
<li><a href="https://github.com/ganelson/inweb"><img src="../docs-assets/github.png" height=0> inweb</a></li>
<li><a href="https://github.com/ganelson/intest"><img src="../docs-assets/github.png" height=0> intest</a></li>
</ul>
		</nav>
		<main role="main">
		<!-- Weave of 'How To Include This Module' generated by inweb -->
<div class="breadcrumbs">
    <ul class="crumbs"><li><a href="../index.html">Home</a></li><li><a href="../services.html">Services</a></li><li><a href="index.html">problems</a></li><li><a href="index.html#P">Preliminaries</a></li><li><b>How To Include This Module</b></li></ul></div>
<p class="purpose">What to do to make use of the problems module in a new command-line tool.</p>

<ul class="toc"><li><a href="P-htitm.html#SP1">&#167;1. Status</a></li><li><a href="P-htitm.html#SP2">&#167;2. Importing the module</a></li><li><a href="P-htitm.html#SP3">&#167;3. Using callbacks</a></li></ul><hr class="tocbar">

<p class="commentary firstcommentary"><a id="SP1" class="paragraph-anchor"></a><b>&#167;1. Status.</b>The problems module provided as one of the "services" suite of modules, which means
that it was built with a view to potential incorporation in multiple tools.
It can be found, for example, in <a href="../inform7/index.html" class="internal">inform7</a> and <a href="../problems-test/index.html" class="internal">problems-test</a>.
</p>

<p class="commentary">By convention, the modules considered as "services" have no dependencies on
other modules except for <a href="../foundation/index.html" class="internal">foundation</a> and other "services" modules.
</p>

<p class="commentary">A tool can import <a href="index.html" class="internal">problems</a> only if it also imports <a href="../foundation/index.html" class="internal">foundation</a>,
<a href="../words-module/index.html" class="internal">words</a> and <a href="../syntax-module/index.html" class="internal">syntax</a>.
</p>

<p class="commentary firstcommentary"><a id="SP2" class="paragraph-anchor"></a><b>&#167;2. Importing the module.</b>We'll use the term "parent" to mean the tool which is importing <a href="index.html" class="internal">problems</a>,
that is, which will include its code and be able to use it. As with any
imported module,
</p>

<ul class="items"><li>&#9679; The contents page of the parent's web must identify and locate the
module:
</li></ul>
<pre class="displayed-code all-displayed-code code-font">
<span class="element-syntax">Import</span><span class="plain-syntax">:</span><span class="string-syntax"> somepath/problems</span>
</pre>
<ul class="items"><li>&#9679; The parent must call <span class="extract"><span class="extract-syntax">ProblemsModule::start()</span></span> just after it starts up, and
<span class="extract"><span class="extract-syntax">ProblemsModule::end()</span></span> just before it shuts down. (But just after, and just
before, the corresponding calls to <a href="../foundation/index.html" class="internal">foundation</a>.)
</li></ul>
<p class="commentary firstcommentary"><a id="SP3" class="paragraph-anchor"></a><b>&#167;3. Using callbacks.</b>Shared modules like this one are tweaked in behaviour by defining "callback
functions". This means that the parent might provide a function of its own
which would answer a question put to it by the module, or take some action
on behalf of the module: it's a callback in the sense that the parent is
normally calling the module, but then the module calls the parent back to
ask for data or action.
</p>

<p class="commentary">The problems module has only a few callbacks, and they are all optional. The
following alphabetical list has references to fuller explanations:
</p>

<p class="commentary firstcommentary"><a id="SP4" class="paragraph-anchor"></a><b>&#167;4. </b><span class="extract"><span class="extract-syntax">DESCRIBE_SOURCE_FILE_PROBLEMS_CALLBACK</span></span> can change the description of a
file used in problem messages; Inform uses this to say "the source text" or
"Standard Rules" rather than citing filenames. See <a href="2-pl1.html#SP4" class="internal">ProblemBuffer::copy_source_reference</a>.
</p>

<p class="commentary firstcommentary"><a id="SP5" class="paragraph-anchor"></a><b>&#167;5. </b><span class="extract"><span class="extract-syntax">DOCUMENTATION_REFERENCE_PROBLEMS_CALLBACK</span></span> is invited to add a clickable
link to in-app documentation; if no callback function is provided, no
such links appear. See <a href="2-pl2.html#SP11" class="internal">Problems::problem_documentation_links</a>.
</p>

<p class="commentary firstcommentary"><a id="SP6" class="paragraph-anchor"></a><b>&#167;6. </b><span class="extract"><span class="extract-syntax">ENDING_MESSAGE_PROBLEMS_CALLBACK</span></span> is called just before a problem message
is about to end, and can be used to append some extra wording. See
<a href="2-pl2.html#SP10" class="internal">Problems::issue_problem_end</a>.
</p>

<p class="commentary firstcommentary"><a id="SP7" class="paragraph-anchor"></a><b>&#167;7. </b><span class="extract"><span class="extract-syntax">FIRST_PROBLEMS_CALLBACK</span></span> is called before the first problem in a run is
issued, and takes as an argument the <span class="extract"><span class="extract-syntax">text_stream *</span></span> to which problems are
being written. See <a href="2-pl2.html#SP3" class="internal">Problems::show_problem_location</a>.
</p>

<p class="commentary firstcommentary"><a id="SP8" class="paragraph-anchor"></a><b>&#167;8. </b><span class="extract"><span class="extract-syntax">FORMAT_CONSOLE_PROBLEMS_CALLBACK</span></span> is called when a Problem message is to
be printed to the <span class="extract"><span class="extract-syntax">stderr</span></span> console (it has no effect on the rendering of Problems
in HTML). See <a href="2-pl1.html#SP5" class="internal">ProblemBuffer::output_problem_buffer_to</a>.
</p>

<p class="commentary firstcommentary"><a id="SP9" class="paragraph-anchor"></a><b>&#167;9. </b><span class="extract"><span class="extract-syntax">GLOSS_EXTENSION_SOURCE_FILE_PROBLEMS_CALLBACK</span></span> is called to add a note
like "in the extension Locksmith by Emily Short"; see <a href="2-pl2.html#SP3" class="internal">Problems::show_problem_location</a>.
</p>

<p class="commentary firstcommentary"><a id="SP10" class="paragraph-anchor"></a><b>&#167;10. </b><span class="extract"><span class="extract-syntax">INFORMATIONAL_ADDENDA_PROBLEMS_CALLBACK</span></span> is called just before a problems
report closes, to give it a chance to add informational messages. (<a href="../core-module/index.html" class="internal">core</a>
uses this mechanism to append text such as "There were 3 rooms and 27 things.")
Such addenda are not problems, and do not affect the program's exit code.
See <a href="2-pl1.html#SP7" class="internal">ProblemBuffer::write_reports</a>.
</p>

<p class="commentary firstcommentary"><a id="SP11" class="paragraph-anchor"></a><b>&#167;11. </b><span class="extract"><span class="extract-syntax">START_PROBLEM_FILE_PROBLEMS_CALLBACK</span></span> is called when <a href="index.html" class="internal">problems</a> wants
to open some kind of file for problem messages, with two arguments: the
filename <span class="extract"><span class="extract-syntax">F</span></span> and the stream <span class="extract"><span class="extract-syntax">P</span></span> to open to it. If the callback function wants
this to come to anything, it must perform the file-open, and write any header
material it would like. See <a href="2-pl3.html#SP19" class="internal">StandardProblems::start_problems_report</a>.
</p>

<p class="commentary firstcommentary"><a id="SP12" class="paragraph-anchor"></a><b>&#167;12. </b><span class="extract"><span class="extract-syntax">END_PROBLEM_FILE_PROBLEMS_CALLBACK</span></span> is called when <a href="index.html" class="internal">problems</a> wants
to close this file again. See <a href="2-pl1.html#SP7" class="internal">ProblemBuffer::write_reports</a>.
</p>

<p class="commentary firstcommentary"><a id="SP13" class="paragraph-anchor"></a><b>&#167;13. </b><span class="extract"><span class="extract-syntax">WORDING_FOR_HEADING_NODE_PROBLEMS_CALLBACK</span></span> is called to ask what wording
should be used to describe a heading in problem messages. See
<a href="2-pl2.html#SP3" class="internal">Problems::show_problem_location</a>.
</p>

<nav role="progress"><div class="progresscontainer">
    <ul class="progressbar"><li class="progressprev"><a href="P-wtmd.html">&#10094;</a></li><li class="progresscurrentchapter">P</li><li class="progresssection"><a href="P-wtmd.html">wtmd</a></li><li class="progresscurrent">htitm</li><li class="progresschapter"><a href="1-pm.html">1</a></li><li class="progresschapter"><a href="2-pl0.html">2</a></li><li class="progressnext"><a href="1-pm.html">&#10095;</a></li></ul></div>
</nav><!-- End of weave -->

		</main>
	</body>
</html>

